Full dc recovery

I need to do dc recovery on a sine signal with a variable amplitude. (so its not between +U and -U but between +2U and 0) It is fast enough if the offsets adjusts within minutes. There is a quick hack in the Art of electronics, where they set a diode and a capacitor in series, but this leaves me one diode drop below 0. Is there a nice (possibly standard) circuit that does a full dc recovery. I try to keep the distortion low.

Another way would be quadrature although this would double the frequency. Can anyone recommend a good low distortion chip there.

Staff: Mentor

I need to do dc recovery on a sine signal with a variable amplitude. (so its not between +U and -U but between +2U and 0) It is fast enough if the offsets adjusts within minutes. There is a quick hack in the Art of electronics, where they set a diode and a capacitor in series, but this leaves me one diode drop below 0. Is there a nice (possibly standard) circuit that does a full dc recovery. I try to keep the distortion low.

Another way would be quadrature although this would double the frequency. Can anyone recommend a good low distortion chip there.

You can use an opamp to get rid of the diode drop in rectification and peak detection. You can do a + peak detector and a - peak detector, and then a single stage after that to give you the mean value.